inchi

A self-contained TypeScript wrapper around the official IUPAC InChI C library compiled to WebAssembly. Convert MDL Molfiles to InChI/InChIKey and back, in Node and in the browser, without any external file or fetch — the WASM binary is gzip-compressed and base64-embedded inside the package.

The published library lives in packages/inchi-js/ and is released to npm as inchi-js.

Installation

npm install inchi-js

Quick start

import {
  inchiFromMolfile,
  inchikeyFromInchi,
  molfileFromInchi,
} from 'inchi-js';

const molfile = `\
  Mrv2014 01010100002D

  3  2  0  0  0  0            999 V2000
    0.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    1.0000    0.0000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0
    2.0000    0.0000    0.0000 O   0  0  0  0  0  0  0  0  0  0  0  0
  1  2  1  0  0  0  0
  2  3  1  0  0  0  0
M  END
`;

const { inchi, auxinfo } = await inchiFromMolfile(molfile);
// → 'InChI=1S/C2H6O/c1-2-3/h3H,2H2,1H3'

const { inchikey } = await inchikeyFromInchi(inchi);
// → 'LFQSCWFLJHTTHZ-UHFFFAOYSA-N'

const { molfile: regenerated } = await molfileFromInchi(inchi);

All four conversion functions — inchiFromMolfile, inchikeyFromInchi, molfileFromInchi, and molfileFromAuxinfo — are async: the WASM module is instantiated lazily on first call and cached forever after. See packages/inchi-js/README.md for the full API reference, option strings, and details on how the WASM binary is shipped.

InChI source

The official IUPAC InChI C library lives as a git submodule under vendor/inchi/, pinned to a known commit of IUPAC-InChI/InChI. Clone with:

git clone --recurse-submodules https://github.com/cheminfo/inchi.git
# or if you already cloned:
git submodule update --init --recursive

Working on the library

npm install
npm test            # type-check, lint, and run the test suite

The library source is in packages/inchi-js/src/. npm run build-lib compiles it to packages/inchi-js/lib.

Building the WASM module

The library ships with a pre-built, base64-embedded WASM module at packages/inchi-js/src/wasm/data.ts. To rebuild it from the InChI C source you need Emscripten (emcc) and cmake ≥ 3.15:

npm run build-wasm

This:

1. Configures and compiles vendor/inchi/INCHI-1-SRC/INCHI_BASE and vendor/inchi/INCHI-1-SRC/INCHI_API/libinchi plus the IUPAC inchi_web.c JSON wrapper with emcc into a .wasm + JS glue.
2. Gzips and base64-encodes the resulting .wasm binary into packages/inchi-js/src/wasm/data.ts (next to the auto-generated JS glue at packages/inchi-js/src/wasm/glue.ts).
3. Generates a TypeScript module that decodes + decompresses the binary at load time and instantiates a WebAssembly instance.

The pre-built artifact is checked in so consumers of the npm package never need a C toolchain.

Scripts

Command	Effect
npm run build-lib	Compile the library to packages/inchi-js/lib.
npm run build-wasm	Rebuild the WASM module from vendor/inchi/ (requires emscripten + cmake).
npm test	vitest run --coverage + type-check + eslint + prettier.
npm run test-only	Tests only, skip lint/types.

Credits

This library is a thin TypeScript wrapper around the official IUPAC InChI C software (MIT-licensed). The inchi_web.c JSON-emitting wrapper layer and the emscripten build approach are adapted from IUPAC-InChI/InChI-Web-Demo (also MIT). All trademarks and the InChI algorithm itself belong to IUPAC.